<div class="spinner">
    <!-- trap requires two elements -->
    <a tabindex=0 class="loader"></a>
    <a tabindex=0 (blur)="trap()" #spinner></a>
    <mat-progress-spinner
        class="example-margin"
        [color]="'primary'"
        [mode]="'indeterminate'"
        >
    </mat-progress-spinner>
</div>
